Lisa, who lives with husband Chris, 30, an electrician, added: "I know I sound like a hippy, or a lunatic but my dog helped me on my way to finding out.

"I think she can smell out the hormones on my breath or something, as that would explain how she could detect my cancer and my pregnancies.

"Ever since the cancer has been treated, Marley has gone back to normal. It's like she's done her job.

"It sounds completely unbelievable, but she really does seem to have a sixth sense. She saved my life."

Dr Anne Carter, senior lecturer at Nottingham Trent University's school of animal, rural and environmental sciences, said: "There have been cases where dogs have been known to sniff out and detect cancer in their owners.

"If it's been part of the family for a long time, the dog can often be looking at natural changes that occur in their owners."

An NHS trial is currently under way to prove the principle that medical detection dogs can find breast cancer and have the potential to diagnose other cancers, such as those of the prostate and lung.